Firefox has a handy search box. Currently its default search engine is Google. But you can also add other search engines that directly search Bing.com, Amazon.com and the likes.
Now there is also an Irishionary.com search engine for Firefox (see the official addon page at Mozilla.org). It lets you search the Irishionary Irish dictionary directly from Firefox. The extension was officially accepted by Mozilla this week. Once installed, it looks like this in my Firefox:
Add to Firefox: You can add this search engine to your Firefox at Mozilla.org.
Add to Chrome: Chrome also accepts custom search engines. To add this to Chrome, first visit Irishionary.com (so that it detects the custom search engine). Then in Chrome click Options -> Basic -> Search engines.
Add to Internet Explorer: In Internet Explorer, you could try Tools -> Manage Add-ons -> Search Providors although I haven’t tested this.